function check_compressor(in1, in2)
    if ischar(in1)
        jobj1 = jpeg_read(in1);
        v1 = jobj1.coef_arrays{1};
    elseif isstruct(in1)
        v1 = in1.coef_arrays{1};
    else
        v1 = in1;
    end

    if ischar(in2)
        jobj2 = jpeg_read(in2);
        v2 = jobj2.coef_arrays{1};
    elseif isstruct(in2)
        v2 = in2.coef_arrays{1};  
    else
        v2 = in2;
    end
    q = v1 ~= v2;
    d = v1 - v2;
    fprintf(1,'Different coef : %d\n',sum(q(:)));
    fprintf(1,'MinMax = %d, %d\n',min(d(:)), max(d(:)));
end
